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TNM staging system

The TNM system has been widely adopted in many areas as a replacement for idiosyncratic disease specific systems. The number of Ts Ns and Ms depend on the tumour / site but in general:


T : Tumour
  • Tx : primary tumour cannot be assessed
  • T0 : no evidence of primary tumour
  • Tis carcinoma in situ
  • T1 : site / tumour specific - generally small
  • T2 : site / tumour specific
  • T3 : site / tumour specific - generally large
  • T4 : site / tumour specific but usually refers to direct extension into adjacent organs / tissues.
N : Nodes
  • Nx : nodes cannot be assessed
  • N0 : no evidence of nodal involvement
  • N1 : site / tumour specific
  • N2 : site / tumour specific
  • N3 : site / tumour specific
M : Metastases
  • Mx : presence of metastases cannot be assessed
  • M0 : no evidence of metastases
  • M1 : distant metastases present

Other descriptors

The TNM system has been expanded to include other measures:

  • R : resection status
  • V : vascular invasion


Additional prefixes can be apended to define the TNM stage

  • c : clinical assessment data
  • p : pathological data
  • y : clinical (yc) or pathological (yp) data following ystemic or radiation therapy be it prior to surgery or as a primary treatment
  • r : clinical or pathological staging at the time of retreatment for recurrence or disease progression
  • a : autopsy data


  • m : multiple primary tumours, e.g. T2(m) or T2(5)

In addition TNMs can be combined into stages I , II , III, IV, e.g. lung cancer staging.

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